First off the free movement of people which has basically allowed clubs to stock up on cheaper European players, non EU players are currently subject to work permit restrictions and you'd assume moving forward this will apply to European players.
Also the FA tried previously to impose foreign player restrictions and were told they couldn't restrict European players as it breached work laws, so that has now changed.
The second and more immediate thing is the drop in the pound against the euro. European transfers are conducted in euros so any big money transfers this summer are going to cost a lot more pounds so may put a stop to a few.
With regards to the restriction of free movement, could this help the England team moving forward by restricting the movement of European players.